Electrical feed-through assembly suitable for electronic devices implantable in a human body

ABSTRACT

An electrical feed-through assembly suitable for electronic devices to be implanted in a human body consisting of a titanium coupler provided with a flange into which is fitted an the alumina sleeve. A titanium coupler is fitted over the other end of alumina sleeve and compression joints are formed between the alumina sleeve and the two titanium parts. A platinum wire is sealed in the titanium coupler and extends through the sleeve and titanium coupler. A nickel coating is sputtered onto the inner surface of the titanium coupler to provide a solderable surface. The flange is used to weld the feed-through assembly onto a housing containing such an electronic device.

United States Patent [191 Barr [75] Inventor: Harold N. Barr, Baltimore,Md.

[73] Assignee: Nuclear Battery Corporation,

Columbia, Md.

[22] Filed: June 4, 1974 [21] Appl. No.: 476,299

[52] US. Cl 174/152 GM 52/759; 128/419 P [51] Int. Cl. H01B 17/26 [58]Field of Search l74/50.56, 50.61, 50.63,

[ Nov. 18, 1975 3,835,864 9/1974 Rasor et a1. 128/419 P FOREIGN PATENTSOR APPLlCATIONS 1,278,366 10/1961 France 174/152 GM Primary E.\'aminerLaramie E. Askin Attorney, Agent, or FirmFleit & Jacobson [57] IABSTRACT An electrical feed-through assembly suitable for electronicdevices to be implanted in a human body consisting of a titanium couplerprovided with a flange into which is fitted an the alumina sleeve. Atitanium coupler is fitted over the other end of alumina sleeve andcompression joints are formed between the alumina sleeve and the twotitanium parts. A platinum wire is sealed in the titanium coupler andextends [56] References and through the sleeve and titanium coupler. Anickel UNITED STATES PATENTS coating is sputtered onto the inner surfaceof the tita- 3,137,808 6/1964 Coda et a1. 174/ 152 GM UX nium coupler toprovide a solderable surface. The 3,275,359 9/1966 Graff 403/179 flangeis used to weld the feed-through assembly onto 3,275,901 9/ 1966 Merrittet a1. 174/50.61 X a housing containing such an electronic device.3,404,218 10/1968 Thompson 174/151 X 3,487,536 1/1970 Goldstein 52/759 X5 Claims, 2 Drawing Figures I4 I [A I I2 70 (P fl I0 IO( TITANIUM) I3(TITANIUM) I3 so 22 c% 90(NICKEL FILM) %/(NICKEL 34, 26 27 I 26 I I '1:29 29 40 7, 28(METALIZED ,0? 4O (sow 5942s) 4: SURFACE) (GOLD BRAZE) 36:7 (ALUMINAHO /,j,

I MLUMINABO "520451411250 54 j 3, SURFACE) I ETALI 0 sum-45E) 7, 3,7 1:3L Ii, v;

\ (601.0 BRAZE) 80 (MD BRAZE) US. Patent Nov. 18, 1975 QMNTZNFMSC Nmr ENqtm Q 40w Q at 4.855 Om mNqtm G409 Ow mu vmtbm QMNIEMSCQQ mm D493 0% ENqmm Q69 0% mm kw mm Ufa ELECTRICAL FEED-THROUGH ASSEMBLY SUITABLE FORELECTRONIC DEVICES IMPLANTABLE IN A HUMAN BODY The present inventionrelates to a novel feed-through assembly particularly suited to seal andto serve as a feed-through for a housing containing an electronic devicewhich is destined for implant into the human body, the seal being liquidand gas tight and the feed-through assembly being body compatible.

Manyfeed-throughs are known in the art, all ostensibly serving thepurpose of sealing an electronic device within an enclosure in a liquidand gas-tight fashion while providing electrical feed-through. Despitethe pro-liferation of prior art structures in this field, criticalproblems remain for the particular application concerning theimplantation of an electronic device within the human body. Such devicesmust meet stringent characteristics vis-a-vis being gas-tight andlight-tight and also must exhibit total compatability with the humanbody. Thus far, in the development of the prior, art no feed-throughassembly completely satisfies all stringent requirements imposed upon afeed-through for this special case.

Accordingly, the principal purposes and object of the present inventionare to provide a novel feed-through assembly that satisfies allrequirements for a feedthrough assembly suitable for implantation withina human body.

This object is accomplished, according to the present invention, byusing specific materials, using specific geometric configurations forcomponents, and the combining of these specific materials and componentsinto a unique feed-through assembly which, although bearing asuperficial resemblance to many prior art suggestions in this field,nevertheless, is characterized by specific and unique differences whichserve to make the feed-through assembly of the present inventiondistinctive and completely suitable for implantation into a human bodywhereas similarly appearing prior art suggestions are unsuitable forimplantation into the human body for one or more reasons. Thus, toappreciate the impact of the present invention and to gain an insightinto the extent of its advance, one must pay close attention to detail.The foregoing and other objects and advantages of the present inventionwill become more evident from the following description of the preferredembodiment of the invention when taken in conjunction with the drawingin which FIG. 1 shows in section the inventive feed-through assembly andFIG. 2 shows a further embodiment of the inventive feed'throughassembly. Referring to the drawing, the

feed-through assembly is cylindrical in form with respect to axis AA.The assembly consists of a titanium coupler (CP grade) generallydesignated by the reference numeral which has a cylindrical annularportion or skirt 12 open at one end 14, the right side as shown in thedrawing. The other end of coupler 10 is fashioned with an-integralflange 16. An inwardly extending annular ring 18 having a central axialopening 20 of a diameter less than the opening of the end 14 is locatedbetween flange l6 and annular portion or skirt 12. The ring 18 providesan annular shoulder or surface 22 on the side nearest the end 14 and anannular shoulder or surface 24 on the side nearest the flange portion 16with the outer diameter of the shoulder 24 being less than the outerdiameter of the shoulder22. The inner diameter of both shoulders 22 and24 corresponds to the diameter of the opening 20. The flange portion 16is also annular (cylindrical) and contains on its face nearest end 14 anannular V-burr 26, the purpose for which will become evident from thefollowing. The flange portion 16 has an inner diameter equal to theouter diameter of the shoulder 24.

Received within the annular opening of the flange portion 16 is anannular alumina sleeve 30 the bore of which is identified by referencenumeral32. The outer diameter of the alumina sleeve 30 equals the outerdiameter of shoulder 24 and the alumina sleeve 30 is received within theannular opening of the flange 16 with one end 34 resting againstshoulder 24 and its outer surface 36 engaged with the inner surface 28of the annular flange portion 16. The portion of the outer surface 36 ofthe annular sleeve 30 in contact and engaging inner surface 28 issuitably metalized with titanium by a conventional hydride treatment anda brazed compression joint is formed between surfaces 28 and 36 using asthe braze material pure gold; the braze bead is indicated by thereference numeral 40 in the drawing. As the brazing techniques are wellknown in the art no elaboration is deemed necessary. In the brazing ofsur faces 28 and 36, the braze material, exemplified by the bead 40, isplaced at the junction of the surfaces and upon subjecting this portionof the assembly to sufficient heat, the braze material by appropriateaction enters into the joint between the surfaces. In the preferredembodiment, selection of the brazing material must specifically meet twoprincipal criteria. First, the braze must be made to provide anexcellent seal and second, the braze material must not contain anycomponents objectionable to the human body, and must be completely bodycompatible. The preferred braze material is pure gold as stated above.Other materials, the use of which is not precluded in this inventionwould include gold-nickle, and gold-palladium alloys with or withoutminor amounts of chromium.

The other end of the alumina sleeve 30 has received thereon a titaniumcap 50 (CP grade) having an annular skirt portion 52 whose inner surface54 contacts and engages the surface 36 of the alumina sleeve. Innersurface 56 of the cap 50 bears against and contacts the end face 38 ofthe alumina sleeve 30. The cap 50 is annular in configuration in thesense that a central hole 58 is defined having a diameter approximatelyhalf the inner diameter of the alumina sleeve 30 bounded by surface 32.The inner surface 54 engages and contacts the outer surface 36 ofalumina sleeve 30 and a second compression joint is formed therebetweenlike the first. The brazed bead is identified by the reference number60. The preparation of surface 36 and the technique fof making thecompression joint is the same as that described for the compressionjoint between surfaces 28 and 36. The braze material, like before, ispure gold.

Received within the alumina sleeve 30 is a platinum wire having adiameter equal to the diameter of the hole 58. Wire 70 constitutes theelectrical feed-through and is brazed into the opening 58 byconventional brazing techniques utilizing a pure gold braze as describedpreviously. The braze bead is identified by reference number 80.Platinum wire 70 is 99.5% pure and projects out of cap 50 to the left asshown in the drawing which represents the exterior or outside. Wire 70extends through the alumina sleeve 30 spaced from the surface 32,through the coupler 10 spaced from the surface 20, through the lowercylindrical annular portion l2 spaced from inner surface 13, and theinterior of a housing containing an electrical or electronic devicessought to be implanted within a human body. The housing, not shown,would contain an open mouth, with or without a flange, that would abutagainst surface 27 of 5 the flange 16 in contact with the V-burr 26which serves the purpose of facilitating an electrical welding operationto seal in a perfectly gas-tight, liquid-tight fashion the flange 16 tothe open mouth of the housing or any other opening in the housing.

The inner surface 13 of the lower cylindrical portion 12 contains acoating 90 of pure nickel which has been sputtered onto the surface 13.The purpose of this sputtered nickel film 90 is to provide a surfacethat adheres excellently to titanium and to which one can solder.

The inventive feed-through assembly, as described, enables the flange 16to be sealed onto a housing in a gas-tight, liquid-tight manner tosatisfy the stringent requirements for electronic devices implantable ina human body and leaves exposed to the human body only materials thatare body compatible. An example of such an electronic device would beone to regulate or control heart function. With the flange 16 sealed tothe housing, the platinum wire 70 provides the electrical feed-throughwhereby energy or information can pass into and out of the housing. Thebrazing of the wire 70 in the hole 58 by means of the particular brazematerial, as well as, the two compression joints formed by the titaninumcap 50 and alumina sleeve 30 on the one hand, and by the titanium flangel6 and alumina sleeve 30 on the other hand, using the particular brazematerial provide three additional excellent liquid-tight, gas-tightseals that satisfy the most stringent requirements for such seals andall have the further advantage of total body compatability. One willnote that the free end 53 of the skirt portion 52 is spacedsubstantially from the outer annular surface 29 of the flange 16 so thatthe braze beads 60 and 40 will be kept totally iso-- lated bothphysically and electrically.

To highlight the advantages of the present invention, one can constructa feed-through assembly, according to the teachings of the presentinvention, wherein the flange 16 has a diameter of approximatelyone-fourth of an inch. For this particular model of construction, theplatinum wire 70 is 0.020inch in diameter seated into hole 58 of thetitaniumcap which itself is only 0.140inch in diameter. The aluminasleeve 30 is onetenth of an inch in diameter having an inside diameterof approximately 0.040inch or twice that of the platinum wire 70. Thealumina sleeve 30 is approximately one-sixth of an inch long and thespacing between the end 53 of the titanium cap 50 and the outer surface29 of the flange 16 is approximatelyl/IZ of an inch. The spacing betweenthe platinum wire 70 and surface 13 on the inside of annular portion 12is approximately 0.050inch. The overall length of the unique assembly isapproximately one-third of an inch. One immediately recognizes that afeed-through assembly constructed according to the teaching of thepresent invention can be of relatively small size and yet will meet thestringent liquid-tightness and gas-tightness requirements and willsatisfy all requirements for body compatability. The accomplishment ofthe present inventionrepresents a significant advance in the art.

A modification of the inventive assembly is possible with some sacrificein quality. The modification is shown in FIG. 2. One may eliminate thetitanium cap 50 and use a direct joint between the platinum wire and theinner surface 32 of the alumina sleeve 30. In this instance, however,the diameter of the inner surface 32 is about the same as the diameterof the platinum wire and the inner surface 32 is first metalized byconventional means. A braze ring is applied to the joint between theplatinum wire 70 and the metalized portion of the surface 32 of thealumina sleeve 30 and when subjected to appropriate heat, the braze ringwill liquify and flow between the outer surface of the platinum wire 70and the surface which closely embraces the platinum wire 70 in thisconstructional modification. The braze material used is the same asdescribed previously.

Although the invention has been described in terms of a preferredembodiment, nevertheless changes and modification obvious to one skilledin the art, from a knowledge of these teachings, are deemed to be withinthe purview of the claimed invention.

What is claimed is:

1. An electrical feed-through assembly suitable for electronic devicesimplantable in a human body comprising 1. a titanium coupler includingan annular skirt por tion open at one end, an annulus integrally formedwith the other end of said annular skirt having an inner diameter lessthan the inner diameter of said annular skirt, and an annular flangeintegrally formed with said annulus having a larger outer diameter thanthat of said annulus and having an inner diameter for its opening thatis greater than the inner diameter of said annulus to definetherebetween a shoulder,

2. an alumina sleeve having an outer diameter equal to the innerdiameter of said annular flange and having one end thereof receivedwithin the opening of said annular flange and bearing against saidshoulder,

3. liquid-tight and gas-tight compression joint means formed betweensaid annular flange and the end of said alumina sleeve received thereinand including the inner surface of said annular'flange, the outersurface of said alumina sleeve receiyed within said annular flange, anda braze material, a. said braze material being selected from the groupconsisting of gold, gold-nickel alloys and.

gold-palladium alloys,

4. a platinum wire extending through said alumina sleeve and projectingout of the other end thereof and extending through said titanium couplerand projecting out of the open end of said annular skirt portion, saidwire being spaced from said titanium coupler and the inner surface ofsaid annular skirt portion. 1

5. a nickel film on the inner surface of said annular skirt portion, and

6. liquid-tight and gas-tight means sealing said platinum wire in theother end of said alumina sleeve;

2. An electrical feed-through assembly suitable for electronic devicesimplantable in a human body comprising l. a titanium coupler includingan annular skirt portion open at one end, an annulus integrally formedwith the other end of said annular skirt having an inner diameter lessthan the inner diameter of said annular skirt, and an annular flangeintegrally formed with said annulus having a larger outer diameter thanthat of said annulus and having an inner diameter for its opening thatis greater than the inner diameter of said annulus to definetherebetween a shoulder,

inner diameter less than the inner diameter of said annular skirt, andan annular flange integrally 2. an alumina sleeve having an outerdiameter equal to the inner diameter of said annular flange and havingone end thereof received within the opening of said annular flange andbearing against said shoulder,

3. first liquid-tight and gas-tight compression joint means formedbetween said annular flange and the 2. an alumina sleeve having an outerdiameter equal 5 end of said alumina sleeve received therein and intothe inner diameter of said annular flange and cluding the inner surfaceof said annular flange, the havingone end thereof received within theopening outer surface of said alumina received within said of saidannular flange and bearing against said annular flange and a brazematerial, shoulder, a. said braze material being selected from the 3.liquid-tight and gas-tight compression joint means 10 group consistingof gold, gold-nickel alloys and formed between said annular flange andthe end of gold-palladium alloys, said alumina sleeve received thereinand'including 4. a titanium cap having a central opening received theinner surface of said annular flange, the outer V on the other end ofsaid alumina sleeve with a skirt surface of said alumina sleeve receivedwithin said portion of said cap engaging the outer surface of annularflange, and a braze material, said alumina sleeve in the vicinity ofsaid other end, a. said braze material being selected from the saidskirt portion terminating spaced from said angroup consisting of gold,gold-nickel alloys, and nular flange, gold-palladium alloys, 5. aplatinum wire extending through said alumina 4. a platinum wireextending through said alumina sleeve and projecting out of the openingin said sleeve and projecting out of the other end thereof cap, andextending through said titanium coupler and extending through saidtitanium coupler and and projecting out of the open end of said annularprojecting out of the open end of saidannular skirt skirt portion, saidwire being spaced from said titaportion, said wire being spaced fromsaid titanium nium coupler and the inner surface of said annular couplerand the inner surface of said annular porskirt portion, tion, butfitting closely within said alumina sleeve. 6. a nickel film on theinner surface of said annular 5. a nickel film on the inner surface ofsaid annular skirt portion,

skirt portion, and 7. second liquid-tight and gas-tight compressionjoint 6. a liquid-tight, gas-tight joint means formed bemeans formedbetween the other end of said alutween said wire and said alumina sleeveand includmina sleeve and said cap received thereon and ining thesurface of said wire, the inner surface of cluding the outer surface ofsaid alumina sleeve in said alumina sleeve, and a brazematerial, thevicinity of said other end, the inner surface of a. said braze materialbeing selected from the the skirt portion of said cap, and a brazematerial,

group consisting of gold, gold-nickel alloys, and a. said braze materialbeing selected from the gold-palladium alloys. group consisting of gold,gold-nickel alloys and 3. An electrical feed-through assembly suitablefor gold-palladium alloys,

electronic devices implantable in a human body com- 8. said first andsecond compression joint means prising being spaced apart to bephysically and electrically 1. a titanium coupler including an annularskirt porisolated, and

tion open at one end, an annulus integrally formed 9. liquid-tight andgas-tight means sealing said platiwith the other end of said annularskirt having an 40 num wire in said opening to said cap.

4. An electrical feed-through assembly as defined in claim 3 whereinsaid braze material is pure gold.

5. An electrical feed-through assembly as defined in claim 3 wherein theplane of said annular flange lies normal to the axis of said couplerwith one face thereof nearer said annular skirt and the other facethereof remotefrom said annular skirt, and a V-burr is integrally formedon the face of said annular flange nearer said annular skirt.

1. AN ELECTRICAL FEED-THROUGH ASSEMBLY SUITABLE FOR ELECTRONIC DEVICESINPLANTABLE IN A HUMAN BODY COMPRISING
 1. A TITANIUM COUPLER INCLUDINGAN ANNULAR SKIRT PORTION OPEN AT ONE END, AN ANNULUS INTEGRALLY FORMEDWITH THE OTHER END OF SAID ANNULAR SKIRT HAVING AN INNER DIAMETER LESSTHAN THE INNER DIAMETER OF SAID ANNULAR SKIRT, AND AN ANNULAR FLANGEINTEGRALLY FORMED WITH SAID ANNULUS HAVING A LARGER OUTER DIAMETER THANTHAT OF SAID ANNULUS AND HAVING AN INNER DIAMETER FOR ITS OPENING THATIS GREATER THAN THE INNER DIAMETER OF SAID ANNULUS TO DEFINETHEREBETWEEN A SHOULDER.
 2. AN ALUMINA SLEEVE HAVING AN OUTER DIAMETEREQUAL TO THE INNER DIAMETER OF SAID ANNULAR FLANGE AND HAVING ONE ENDTHEREOF RECEIVED WITHIN THE OPENING OF SAID ANNULAR FLANGE ANDBEARINGAGAINST SAID SHOULDER,
 2. an alumina sleeve having an outer diameterequal to the inner diameter of said annular flange and having one endthereof received within the opening of said annular flange and bearingagainst said shoulder,
 2. An electrical feed-through assembly suitablefor electronic devices implantable in a human body comprising
 2. analumina sleeve having an outer diameter equal to the inner diameter ofsaid annular flange and having one end thereof received within theopening of said annular flange and bearing against said shoulder,
 2. analumina sleeve having an outer diameter equal to the inner diameter ofsaid annular flange and having one end thereof received within theopening of said annular flange and bearing against said shoulder,
 3. Anelectrical feed-through assembly suitable for electronic devicesimplantable in a human body comprising
 3. first liquid-tight andgas-tight compression joint means formed between said annular flange andthe end of said alumina sleeve received therein and including the innersurface of said annular flange, the outer surface of said aluminareceived within said annular flange and a braze material, a. said brazematerial being selected from the group consisting of gold, gold-nickelalloys and gold-palladium alloys,
 3. liquid-tight and gas-tightcompression joint means formed between said annular flange and the endof said alumina sleeve received therein and including the inner surfaceof said annular flange, the outer surface of said alumina sleevereceived within said annular flange, and a braze material, a. said brazematerial being selected from the group consisting of gold, gold-nickelalloys, and gold-palladium alloys,
 3. liquid-tight and gas-tightcompression joint means formed between said annular flange and the endof said alumina sleeve received therein and including the inner surfaceof said annular flange, the outer surface of said alumina sleevereceived within said annular flange, and a braze material, a. said brazematerial being selected from the group consisting of gold, gold-nickelalloys and gold-palladium alloys,
 3. LIQUID-TIGHT AND GAS-TIGHTCOMPRESSION JOINT MEANS FORMED BETWEEN SAID ANNULAR FLANGE AND THE ENDOF SAID ALUMINA SLEEVE RECEIVED THEREIN AND INCLUDING THE INNER SURFACEOF SAID ANNULAR FLANGE, THE OUTER SURFACE OF SAID ALUMINA SLEEVERECEIVED WITHIN SAID ANNULAR FLANGE, AND A BRAZE MATERIAL, A. SAID BRAZEMATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF GOLD, GOLD-NICKELALLOYS AND GOLD-PALLADIUM ALLOYS,
 4. A PLATINUM WIRE EXTENDING THROUGHSAID ALUMINA SLEEVE AND PROJECTING OUT OF THE OTHER END THEREOF ANDEXTENDING THROUGH SAID TITANIUM COUPLER AND PROJECTING OUT OF THE OPENEND OF SAID ANNULAR SKIRT PORTION, SAID WIRE BEING SPACED FROM SAIDTITANIUM COUPLER AND THE INNER SURFACE OF SAID ANNULAR SKIRT PORTION. 4.a platinum wire extending through said alumina sleeve and projecting outof the other end thereof and extending through said titanium coupler andprojecting out of the open end of said annular skirt portion, said wirebeing spaced from said titanium coupler and the inner surface of saidannular skirt portion.
 4. An electrical feed-through assembly as definedin claim 3 wherein said braze material is pure gold.
 4. a platinum wireextending through said alumina sleeve and projecting out of the oTherend thereof and extending through said titanium coupler and projectingout of the open end of said annular skirt portion, said wire beingspaced from said titanium coupler and the inner surface of said annularportion, but fitting closely within said alumina sleeve.
 4. a titaniumcap having a central opening received on the other end of said aluminasleeve with a skirt portion of said cap engaging the outer surface ofsaid alumina sleeve in the vicinity of said other end, said skirtportion terminating spaced from said annular flange,
 5. a nickel film onthe inner surface of said annular skirt portion, and
 5. An electricalfeed-through assembly as defined in claim 3 wherein the plane of saidannular flange lies normal to the axis of said coupler with one facethereof nearer said annular skirt and the other face thereof remote fromsaid annular skirt, and a V-burr is integrally formed on the face ofsaid annular flange nearer said annular skirt.
 5. a platinum wireextending through said alumina sleeve and projecting out of the openingin said cap, and extending through said titanium coupler and projectingout of the open end of said annular skirt portion, said wire beingspaced from said titanium coupler and the inner surface of said annularskirt portion,
 5. a nickel film on the inner surface of said annularskirt portion, and
 5. A NICKEL FILM ON THE INNER SURFACE OF SAID ANNULARSKIRT PORTION, AND
 6. LIQUID-TIGHT AND GAS-TIGHT MEANS SEALING SAIDPLATINUM WIRE IN THE OTHER END OF SAID ALUMINA SLEEVE.
 6. liquid-tightand gas-tight means sealing said platinum wire in the other end of saidalumina sleeve.
 6. a nickel film on the inner surface of said annularskirt portion,
 6. a liquid-tight, gas-tight joint means formed betweensaid wire and said alumina sleeve and including the surface of saidwire, the inner surface of said alumina sleeve, and a braze material, a.said braze material being selected from the group consisting of gold,gold-nickel alloys, and gold-palladium alloys.
 7. second liquid-tightand gas-tight compression joint means formed between the other end ofsaid alumina sleeve and said cap received thereon and including theouter surface of said alumina sleeve in the vicinity of said other end,the inner surface of the skirt portion of said cap, and a brazematerial, a. said braze material being selected from the groupconsisting of gold, gold-nickel alloys and gold-palladium alloys, 8.said first and second compression joint means being spaced apart to bephysically and electrically isolated, and
 9. liquid-tight and gas-tightmeans sealing said platinum wire in said opening to said cap.